What you're looking at here is an actual Wii-like 3-D controller interface that can track objects like your hand in real time. It may look a little shoddy, but what's amazing is that this very functional 3-D interface was built by a hobbyist with parts most DIYers can find in their couch cushions—six resistors, aluminum foil, wire, a cardboard box, and an Arduino microprocessor to crunch the numbers. That's it. It couldn't be more simple. But how'd he pull it off?
The rig uses simple RC circuits to sense the distance of an object in relation to a set of capacitive plates (here, the aluminum foil with current running through it). The circuits feed their data to the Arduino, which processes them with builder kylemcdonald's custom Processing code (an open-source graphical programming language), and spits out raw 3-D coordinates that update 10 times per second for each sensor. Just a hint of the amazing things accomplished tinkerers can pull off with hackable microprocessors like the Arduino. [Instructables via Hack-a-Day]